1. Field of the Invention
The present invention relates generally to transmission sump filters for powered vehicles. More specifically, the present invention concerns a transmission fluid filter having a uniquely configured bypass valve that operates to efficiently and effectively direct fluid to a transmission pump without passing it through a filter media in conditions when bypass is desirable (e.g., cold and start-up conditions).
2. Discussion of Prior Art
In a powered vehicle having a lubricated transmission, it is desirable to filter debris (e.g., solid particles, impurities, etc.) out of the fluid in the transmission sump prior to the fluid entering the transmission pump. Known prior art filters utilize a porous filter media fluidly interposed between the sump and the pump to filter the fluid. Unfortunately, these prior art filters are problematic because in certain conditions (e.g., cold and start-up conditions), the fluid is not adequately sucked through the filter media (e.g., the fluid is too viscous) and thus fluid is not sufficiently provided to the pump.
Some prior art filters utilize a bypass valve to bypass the filter media during these conditions when bypass is desired. These prior art filter bypass valves; however, are problematic in that they are costly to construct, unreliable, and ineffective and inefficient in providing sufficient fluid to the pump during bypass conditions.
The present invention provides an improved filter that does not suffer from the problems and limitations of prior art filters set forth above. The inventive filter provides a bypass valve that reliably operates when bypass is desired, reliably closes when bypass is not desired, and effectively and efficiently provides fluid to the pump when in operation. The inventive filter further provides a bypass valve that is simple and inexpensive to construct.
A first aspect of the present invention concerns a filter broadly including a filter housing presenting a filter inlet, a bypass inlet, and an outlet; filter media in the housing such that fluid flowing from the filter inlet to the outlet passes through the media and fluid flows from the bypass inlet to the outlet without passing through the media; and a bypass valve assembly shiftable into and out of a closed position in which fluid flow through the bypass inlet is prevented. The bypass inlet is defined about a bypass inlet axis and the outlet is defined about an outlet axis, wherein the axes are at least substantially parallel and at least in close proximity to one another.
A second aspect of the invention concerns a filter wherein the bypass valve assembly includes a projecting valve seat and a valve body shiftable in a first direction into and out of sealing engagement with the valve seat. The valve body includes a first positioning element extending toward the valve seat and cooperating therewith to restrict movement of the valve body in a second direction, wherein the first and second directions are at least generally unparallel to one another.
A third aspect of the present invention concerns a filter wherein the bypass valve assembly further includes a lug operable to limit the range of movement of the valve body in the first direction to a path and the valve body is configured to cooperate with the lug and the valve seat to restrict, along the entire path, movement of the valve body in the second direction.
A fourth aspect of the present invention concerns a filter wherein the bypass valve assembly broadly includes a biasing mechanism yieldably biasing the assembly into the closed position. The mechanism is configured so that the yieldable biasing force provided thereby varies depending on temperature.
Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment and the accompanying drawing figures.